Probable bugs

'var_export' or 'print_r' call is used without 'return' argument: Reports var_export() and print_r() calls without the return argument when their results are explicitly used.
Assignment in condition: Reports the assignments that are used in conditional expressions.
Case with specified value not found in enum: Reports the arguments of enum's from method calls that are not found in target enum classes.
Concatenation with arithmetic usage: Reports the string concatenation expressions that are used together with +, -, <<, and >> operators.
Constant reassignment: Reports reassignments of constants.
Division by zero: Reports division by zero or modulo by zero.
Duplicate arm in 'match' expression: Reports duplicate bodies in match arms.
Duplicate array keys: Reports duplicate keys in array declarations.
Duplicate branch in switch statement: Reports the switch statements containing the same code in different branches.
Duplicate case in switch statement: Reports duplicate case expressions in switch statements.
Duplicate character in function call: Reports duplicate characters provided in the characters argument of functions like ltrim or str_words_counts.
Duplicate condition: Reports duplicate conditions in match expressions.
Empty index operator not supported for strings: Reports the usages of empty index operator ([]) on strings.
Expression result unused: Reports the expressions that are calculated, but the calculation result is not used anywhere.
Field reference does not match object shape: Reports reference to a property whose name does not match the name specified via an #[ObjectShape] attribute or in the PHPDoc comment.
Foreach array is used as value: Reports the variables that are used in a foreach loop as both an array expression and an array's key or value (for example, foreach ($items as $items) {}).
Format function parameters mismatch: Reports the arguments of a format function (such as printf or sprintf) that are not mapped to any parameters or specification conversions.
Goto into loop statement: Reports the goto labels that are located inside loops or switch statements.
Invalid function result used: Reports the usages of a void or never function's return value.
Invalid string offset usage: Reports invalid string offset usages that will result in a runtime error.
Invalid type of unpacked argument: Reports unpacked function arguments and array elements whose type is neither array nor Traversable.
Local object is used only for writing properties: Reports the variable assignments to new objects that are used only for writing the object's properties without observable side effects.
Method '__toString' implementation: Reports the attempts to convert the objects having no __toString method implementation to string.
Method '__toString' return type: Reports the __toString methods that do not return string.
Misordered 'rand' function arguments: Reports the rand($min, $max) family function calls in which the max argument is less than min.
Missing 'break' statement: Reports the case clauses in switch statements that do not end with a break or a return statement.
Missing parent call for constructor: Reports the constructors that do not call their parent constructor.
Missing parent call for magic methods: Reports the magic methods that do not call their parent magic method.
Missing parent call for method: Reports the methods that do not call their parent method.
Modification of the array returned from function by value won't have any effect: Reports call to a function that returns array by value, which makes the assignment operation non-working.
Nested vs outer 'foreach' variables conflict: Reports the variables that are used as a key or value both by the inner and outer foreach loops.
Non-strict object equality: Reports the usages of the comparison operator (==) for comparing object variables.
Optional before required parameter: Reports the optional parameters that appear before the required parameters in a function/method declaration.
Pass parameter by reference: Reports the arguments in a function/method call that cannot be passed by reference.
Private method may be inaccessible during late static binding call: Reports the late static binding method calls (that is, performed via static::) that may be resolved to inaccessible private methods from child classes.
Redeclaration of standard library function: Reports the redeclaration of standard library functions.
Redundant assignment: Reports the assignment statements, in which both sides are equal.
Some enum cases are uncovered: Reports the match expressions that don't cover all enum cases in match arm conditions.
Statement has empty body: Reports the statements that have empty bodies.
Strict comparison of operands with incompatible types: Reports the === or !== strict comparisons used on operands with incompatible types.
Suspicious names combination: Reports the assignments and function calls where the name of the variable or parameter probably doesn't match the name of the assigned or passed value.
Switch statement without default branch: Reports the switch statements without a default branch.
Unnecessary statement use: Reports the use statements that contain non-fully qualified class names and thus have no effect.
Unused 'match' condition: Reports the conditions in match expressions that will never be matched.
Unused 'switch' branch: Reports the branches in switch statements that do not belong to the set of enum cases and as a result are never executed.
Wrong string concatenation: Reports the attempts to concatenate strings by using the + operator instead of the dot (.) concatenation operator.

Last modified: 18 June 2024